Almost 30 million Americans are affected by osteoporosis with over 1.8 million osteoporotic fractures occurring each year, and these figures will increase significantly as the American population ages. Nutritional intake is known to affect bone and is a potentially modifiable factor. Traditionally, calcium and vitamin D have been the focus in most nutrition studies addressing bone health. As such, relatively little is known about the role of dietary protein on skeletal health. We propose to examine dietary protein and age- related bone loss from different skeletal sites. Dietary factors represent an important understudied area in osteoporosis and this work will allow us to better understanding ways to preserve bone as well as insights into the possible mechanisms for a protein influence on bone mineral density (BMD). This study proposes to examine associations between dietary protein and bone mass, longitudinal bone loss of the hip and spine, falls and hip fracture over 8-13 year follow-up among the population-based Framingham Cohort. Specifically, using a well-characterized cohort, the 4 specific aims of this study will examine the possible pathway between dietary protein intakes and skeletal health via: 1) BMD, 2) bone loss, 3) lean mass and falls, and 4) hip fracture. The richness of the data collected by the Framingham Study will also permit us to examine other factors that may be on the pathway between dietary protein intake and bone health. This project will make extensive use of the resources and data already collected from previous Framingham grants. Thus, by leveraging these data resources, our proposed study will be able to achieve its goals at lower cost, and extend the investigation of nutritional influences upon bone into important new areas that were previously unexplored. The proposed study will provide essential information on associations of keen interest both to clinical medicine and public health. Better understanding of potentially modifiable factors such as dietary protein may help us make more reliable public health interventions targeted at preserving bone. Bone loss and osteoporosis are serious burdens for many older individuals. This study will provide insights on potential mechanisms to reduce osteoporotic risks. Based on strong preliminary data, this study will provide new and important information about the role of dietary protein upon bone outcomes in older men and women. Dietary factors are poorly understood, yet potentially modifiable. More information is needed on the precise effects of dietary protein on bone health for community-based men and women.